Generally, in fields where information security is required, authentication technology is adopted, which uses secret information and secret code shared between two entities, as a measure to prove his or her validity.
For example, an IC chip is included in an IC card (Smart Card) used for electric settlement. The IC chip stores an ID for identifying the IC card and secret information. Furthermore, the IC card has a function of an encryption process for conducting an authentication based on the ID and the secret information.
As another example of a copyright protection technology for content data, content protection technology for proving the validity of the SD card (a registered trademark) is known (Content Protection for Recordable Media (CPRM)).
[Antecedent Technical Document]
    Non-patent document 1: Content Protection for Recordable Media (CPRM), http://www.4centity.com/    Non-patent document 2: Media Identifier Management Technology (MIMT), http://www.4ecntity.com/    Non-patent document 3: D. Naor, M. Naor and J. Lotspiech, “Revocation and Tracing Schemes for Stateless Receivers,” Proc. CRYPTO 2001, LNCS2139, Springer-Verlag, pp. 41-62, 2001